AM (Amplitude Modulation) radio often sounds “foggier” or less clear compared to FM (Frequency Modulation) radio due to several key differences in how these radio signals are transmitted and received:
- Modulation Method: AM radio uses amplitude modulation, where the audio signal’s strength (amplitude) is varied to encode information. This method is more susceptible to atmospheric interference, electrical noise, and electromagnetic interference (EMI) from various sources like power lines, lightning, and electronic devices. As a result, AM signals can suffer from more noise and distortion, leading to a less clear and more “foggy” sound quality, especially over longer distances.
- Bandwidth and Frequency Range: FM radio, on the other hand, uses frequency modulation, where the audio signal’s frequency is varied to encode information. FM signals occupy a wider bandwidth and are less affected by atmospheric and electrical noise compared to AM signals. This allows FM radio to deliver clearer, more consistent sound quality with less interference and noise, contributing to a richer and more detailed audio experience.
- Audio Fidelity: FM radio is capable of reproducing a wider range of audio frequencies with greater fidelity compared to AM radio. FM signals can transmit higher frequencies and maintain better signal-to-noise ratios, resulting in a more natural and richer sound reproduction. In contrast, AM radio is limited in its frequency response and dynamic range, which can affect the clarity and richness of audio content, especially in music and high-fidelity audio transmissions.
- Noise and Interference: AM radio is inherently more susceptible to noise and interference because its reception quality depends largely on the amplitude of the transmitted signal. Atmospheric conditions, electrical noise from power lines and appliances, and other radio frequency interference sources can degrade AM radio reception, leading to a noisy and less clear sound. FM radio, with its frequency modulation technique and wider bandwidth, can better reject noise and interference, resulting in a quieter and more consistent audio experience.
- Sound Quality Comparison: Overall, FM radio is generally perceived to have better sound quality than AM radio, especially in terms of clarity, fidelity, and resistance to noise. FM’s ability to transmit higher frequencies and its resistance to atmospheric and electrical interference contribute to a more enjoyable listening experience, particularly for music and high-quality audio content.
In summary, the differences in modulation techniques, bandwidth, frequency response, and susceptibility to noise and interference contribute to why AM radio often sounds foggier or less clear compared to FM radio, which is known for its richer sound quality and better resistance to noise.